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Discussion Starter #1
Ok, I'm not all that experienced with transmissions so I thought I'd reach out to the VMF for some suggestions before proceeding. Here's the cliff note version.

C4 rebuilt out of car while engine was removed and rebuilt. Installed engine and C4 in early April. Not a leak from the engine or the tranny. Everything performs as expected. I've put on maybe 350 miles between April and now.

Fast forward to today. Car has been sitting for nearly two weeks as I'm waiting for AMK to return an alternator being repaired under warranty. I glance at the car and notice a large pool of transmission fluid (maybe 1-2 qts). I jack up the car and scoot under for look.

The usual suspects on the passenger side of tranny look dry (filler tube base, modulator). The fluid is dripping off the back of pan (rear of car). I check out the speedo and it looks a little wet, but is not dripping and even if it was, it wouldn't have pooled in the right area.

Ok....I look at the area of the neutral start switch, etc. It looks like the fluid is coming from somewhere up there, but it's hard to tell. I know remote diagnosis is impossible, but assuming bolts are torqued properly (which they are), what could have failed on the transmission while parked? Any gotcha's on that side of the transmission?

Any pearls of wisdom are appreciated. Thanks. Kevin
 

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Based on the leak comming from the switch, it could be the "O" ring seal where the shifter shaft goes into the casing.
 
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I've seen the same problem before. After the vehicle sits for an exteneded period the torque converter slowly drains its fluid into the transmission pan, filling it to an abnormally high level and aggravating any leak spots. As for the exact cause of the leak, you may want to clean the entire transmission exterior of fluid with rags and cleaner. Then watch for a couple of days as the leak reappears to see exactly where it is coming from.
I have seen the shift linkage rod seal pop partially out of its bore causing a fairly large leak in a C4. You also may want to double check the pan bolts for proper tightness. They should be just tight enough just begin to squish the gasket out around the pan. Any tighter and your asking for leaks. Finally I have seen leaks from the pressure test port on the passenger side of the C4 about half way up on the case.

Hope this helps.

'68 Coupe - '70 Fastback - '99 GT
 

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Discussion Starter #4
Thanks for both of the replies. I will go ahead and clean up the case so I can pinpoint the exact location of the leak.

It's not the end of the world, but it sure is a bummer when you pay good $ to have it rebuilt and 3 months later it's leaking. Oh well, that's why our Mustang's are a labor of love.

Thanks again. Kevin
 

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My money is on a leaky converter check valve in the front pump...

Same thing has happened to me on the race car....mainly because it sat a lot between races.

Keep your eyes peeled for a leak from the case vent tube....That should clinch it...
 

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I've had a leak from the same area that came from a defective selector shaft seal underneath the neutral/backup switch. I could see where this would be neglected by rebuilders in a hurry or damaged re-installing linkage.

I think probably a bad seal. Gonna be tough to replace withour R&R the transmission.
 
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